Toyota Corolla, 135,000 miles, plugs replaced @ 100,000. CEL came on a while ago P0351, ignition coil cyl 1, after a rough start and idle. Turned the car off restarted and the car ran fine but CEL still on. Cleared code. Swapped coil between 1&2, few weeks later same code and rough start Again, turned car off restart and ran fine. Cleared code. A few weeks later same thing, swapped plug bet 1 & 2.. Today same symptom and same code. It may be my imagination but the car may be running a little rough, but I may also be looking for problems since the 1st CEL. Mileage has not changed. The CEL is always for coil 1. Any ideas on what to check next? Harness or fuel injection? Thanks much!